Set to underpin the German carmaker's expansive spread at this week's Geneva motor show, the advanced four-wheel drive showcases a new plug-in diesel-electric system that Volkswagen is developing for use in upcoming production models. The drivetrain is claimed to provide the updated 4,096-pound Cross Coupe with combined fuel consumption of 131 mpg (U.S.) on the European test cycle.

The new hybrid system, which replaces the similarly conceived gasoline-electric arrangement of the initial Cross Coupe concept, mates a 187-hp version of Volkswagen's new 2.0-liter, four-cylinder common-rail diesel engine, complete with twin balance shafts, with a pair of electric motors--one up front delivering 54 hp and in combination with the diesel engine providing drive to the front wheels. The other electric motor is mounted at the rear with 114 hp and driving the rear wheels.

The electric motors, produced in house at Volkswagen's Braunschweig-based R&D center in Germany, are driven by a 9.8 kilowatt-hour lithium-ion battery pack sitting in the central tunnel. The pack is charged by plugging in, or via regenerative kinetic energy produced on the run or, in range-extender mode, direct from the diesel engine.

With a combined system output of 302 hp and up to 516 lb-ft of torque--295 lb-ft of which is available from just 1,750 rpm--the latest Cross Coupe is claimed to hit 62 mph from standstill in 6.5 seconds and reach a top speed limited to 137mph.

With the claimed 131 mpg, the vehicle's range stretches to 800 miles in hybrid mode on its 14.5-gallon fuel tank. By comparison, the earlier gasoline-electric Cross Coupe concept averaged 105 mpg.

When running on the diesel engine alone at light throttle, the Cross Coupe is driven by its front wheels. Under what Volkswagen describes as "enthusiastic driving," the electric motors join in to deliver power to all four wheels. In off-road mode, the diesel engine combines with the rear electric motor to provide optimum traction.

In pure-electric mode, at which its top speed is limited to 80 mph, Volkswagen's latest concept is said to have a range of up to 28 miles. The driver can choose between hybrid or electric-drive modes via a switch on the center console.

In electric mode a clutch is opened to disengage the diesel engine, reducing mechanical drag. If, however, additional battery charge is required to power the electric motors, the diesel engine springs to life to top up the battery.